Field of the Invention
Embodiments of the invention generally relate to the field of dentistry and, specifically, to printing aided techniques used with dentures and molds for printing. Embodiments include a component that transfers position, direction and rotation information of an implant installed in a patient's mouth or in a mold to be used in scanning equipment.
Description of the Related Art
Generally, dental implants are used as supports to replace one or more missing teeth. The implant, also known as abutment, is typically the first of at least two parts of dental restoration that also includes one or more prosthetic elements fixed to the implant by means of a screw. The prosthetic elements are responsible for aesthetic replacement of missing teeth and usually consist of an intermediate structural component known as a connection; and aesthetic replacement, known as a crown, commonly attached through adhesive or cement suitable for dental use. In some cases only a prosthetic component is used, combining structural and aesthetic function, for one or more missing teeth.
Generally, the success of restoration depends on the stability of the entire set, particularly the absence of relative movement between the abutment and the prosthetic elements. For this purpose, the abutment typically includes, in its upper portion, a hexagonal or octagonal-shaped coupling as an anti-rotation element, or other geometric form to prevent rotation, even amorphous, which is applied directly to a surface or inside of a conical recess usually known as a Morse taper.
Generally, the prosthetic element, in turn, is coupled to the abutment, topically connected, and includes complementary coupling geometry, whether anti-rotation or not (as the case may be), so that when the connection and abutment are coupled in the mouth, the cooperation between the anti-rotation elements prevents the relative movement between these components or, in case of prosthesis supported on multiple implants, the disposition itself of more than one supporting point to prevent the relative movement. Thus, typically, the screw that holds the connection to the abutment is used only to prevent the separation of these two parts and does not prevent the relative rotation movement among them, by minimizing the strain on the screw and expanding its cycle life.
Generally, the presence of these anti-rotation elements requires additional care on the manufacture of prosthetic component so that, when installed, the internal surfaces and external prosthesis remain aligned to those of nearby teeth. For this purpose, as will be discussed herein, it is necessary to measure not only the position (x, y, and z), but also the direction (in angles around each one of the axes x, y, and z), as well as the anti-rotation fixing element alignment in the mouth, that is, in which direction the corners of this anti-rotation element are located such that these measurements are considered in the manufacture of the connection and are reflected on how the aesthetic portion is concocted in relation to underlying anti-rotation element. This occurs because, even if the installation is carefully made to achieve a specific alignment, certain micro movements during the healing phase may lead to loss of alignment.
Generally, when the prosthetic element is supported on multiple implants, for instance, in the case of a prosthetic bridge, the position and direction of the abutment is vital information to avoid prosthesis settlement issues that may occur when, due to misalignment of given connection elements makes up the bridge, the dentist is bound to force or fit the component so that it may be implanted.
Currently, after a period of healing in which the implant remains closed under the gums, it is exposed in the mouth for the mounting of a healing connection. During the process, the position of the implant may be captured by physical molding or directly to the computer by means of a scanning process. For example, as described in U.S. Pat. No. 5,829,981 to Ziegler, entitled “One-Piece Impression Coping for Customized Implant Restorative Systems”, the physical molding process, a printing workpiece capable of connecting the anti-rotation element of the implant, is stuck to it and the printing of the whole mandibular arch is made by capturing the workpiece. Afterwards, the printing is removed from mouth and a component similar to the implant is fixed to the same workpiece and the set gets a coat of plaster or a similar molding material so as to get a model of the patient's mandibular arch after the healing of the implant.
Typically, this step was followed by manual molding of the desired prosthetic component, generally in wax, for further casting in biocompatible metal (such as gold) and aligning problems were solve by adding intermediary components as those described in U.S. Pat. No. 4,988,297 to Lazzara et al, entitled “Alignment Corrector for Dental Implants”. However, computer-aided design/computer-aided manufacturing (CAD/CAM) technologies for prosthetic components, for example as described in U.S. Pat. No. 4,742,464 to Duret et al., entitled “Method of Making a Prosthesis, Especially a Dental Prosthesis”, and, particularly, from blocks that include the prefabricated anti-rotation element, as discussed in U.S. Pat. No. 6,991,853 to Branco de Luca, entitled “Blank From Which a Customized Prosthetic Part Can Be Machined”, have paved the way for the manufacturing of connections through the computer without the need for manual molding or wax works.
For this purpose, generally, data about the position and orientation of the implant needs to be informed to the computer, which is done by means of intra-oral scanning, for example using laser infrared cameras or scanners, as described in U.S. Pat. No. 4,575,805 to Moermann et al., entitled “Method and Apparatus for the Fabrication of Custom-Shaped Implants”, and in U.S. Pat. No. 4,837,732 to Brandestini et al., entitled “Method and Apparatus for the Three-Dimensional Registration and Di splay of Prepared Teeth”.
However, it is difficult to work with scanning media directly inside the mouth, especially due to access difficulties, limited space, poor lighting, and the presence of fluids (such as saliva), which cause undesired reflexes that may affect the quality of the scanning and compromise the accuracy of the measurement. Capturing the anti-rotation element at the top of the implant when it might be hidden, in fluids or covered by close elements is particularly challenging, which frequently leads to errors that need to be later balanced.
In order to prevent errors, CAD/CAM system manufacturers started to employ measurement devices or scanning transfers, as indicated by reference number 35 in U.S. Pat. No. 8,480,396 to Saliger et al., entitled “Method for Automatically Fabricating a Dental Superstructure for Attachment to an Implant”, which is intended to highlight the position and orientation of the implant for the scanning device. Such transfers, typically, may be placed in the mouth or over the plaster mold produced with the help of a printing piece, as previously performed. Generally, the advantage of the mold is the possibility of sending it to a laboratory when the dentist does not have the equipment for intra-oral scanning. The use of the mold as a basis for the scanning of the implant's position and orientation allows the use of scanning methods that are cheaper and larger, which cannot be used intra-orally.
Scanbodies used to determine the position and orientation of components as implants are endowed with a specific technique. For example, U.S. Pat. No. 8,747,112 to Brun, entitled “Abutment Position Locator”, describes a workpiece to be fitted in a dental implant in an orientation that defines an ‘X’ insertion central axis and a ‘D’ insertion direction of the workpiece. According to Brun, the workpiece includes a flat bevel angle in its upper portion and a fit connection, and the implant has a resilient spring member in its lower portion for preventing its displacement relative to the implant when inserted into the dental implant.
For example, European Patent 2130514 to Scherberger, entitled “Abutment With Optically Detectable Elements Defining its Position and Orientation”, describes a scanning item endowed with a beveled surface to enable optical scanning. According to Scherberger, the flat bevel angle extends itself over the length of the workpiece and its larger part is next to the base and its smaller part is closer to the top, and the width between the two edges decreases steadily. As discussed in Scherberger, the member is used solely for detection, and the same may be done in low-reflection material, reducing the need for adding non-reflective material.
As per the aforementioned documents, as well as according to components available in the market, state-of-the-art scanbodies use flat surfaces over a generally cylindrical body to determine the orientation of the implant and, specifically, the orientation of the anti-rotation element of the implant. This flat surface is generally in the form of a laminate or key way or, as a prismatic element comprised of multiple flat surfaces as discussed in European Patent 2218423 to Lawitschka et al., entitled “Determining Position and Orientation of a Dental Implant”.
The problem with typical scanners is that its geometry generates artifacts, also referred to as errors, during scanning. Such artifacts occur due to the way the light emitted by scanners interacts with flat surfaces of the pieces. Such errors are compensated in a post-processing step, which prolongs the scanning process. Sometimes, when the measuring error is significant even after further processing, it is necessary to cover the piece with opaque sprays or non-reflective powder before a new measurement is performed.
Furthermore, when the piece does not present flat surfaces, as discussed in European Patent 2400917 to Eriksson et al., entitled “Device for Indicating the Position and Orientation of a Dental Implant”, it is not possible to locate the orientation of the anti-rotation element on the abutment head. For example, the scanbody as presented in Eriksson et al., is also subject to problems in the identification of implant position and direction when it is set between remaining dental elements and only functions efficiently in the case of tooth loss.
Also, the material currently used in the making of scanners presents problems. Metal used in several aforementioned manners is expensive and presents shiny surfaces after machining. The plastic materials, on the other hand, are typically manufactured by an injection process to minimize costs. However, the injection process results in a nearly polished finishing, which highlights the shine problems, demanding the use of opaque sprays. Among the plastic materials used in the injection process, typically, natural Polyether Ether Ketone (PEEK) is one of the most widely used. However, generally, PEEK does not present good performance during the scanning process due to reflection. As such in view of the above, there is a need for a more efficient product, which may be totally and flawlessly scanned and which guarantees quality and accuracy to the scanning process in any type of scanner.